Hybrid car leader Toyota and BMW are joining forces in pursuit of a better vehicle battery.

The two automakers today announced a research partnership around basic research to speed development of next-generation lithium ion battery cells.

As part of the collaboration, BMW will supply its "clean diesel" engines to Toyota for vehicles sold in Europe. The 1.6-liter and 2.0-liter diesel engines are slated for certain Toyota models in Europe starting in 2014, the companies said.

The joint research is designed to give the two companies a leg up on competitors for core technology in cleaner, fuel-efficient vehicles, company representatives said today during a joint press conference at the Tokyo Motor Show.

"Battery technology is crucial for hybrid technology but also for the future of individual mobility," said BMW board member Klaus Draeger at the press conference. "Whoever has the best batteries in terms of function, cost, and quality in their vehicles will win more customers."

The "medium to long-term" research will aim to develop improved batteries for both hybrids and electric vehicles, he said. The memorandum of understanding between the companies also opens up the possibility for collaboration in other projects.

Toyota is well advanced in pursuit of hybrids, which it will expand next year with a family of Prius vehicles. It also has a partnership with Tesla Motors which is supplying the electric powertrain, including Panasonic battery cells, for Toyota's upcoming RAV4 Electric Vehicle.

BMW is intent on bringing hybrid and electric vehicle technology to the premium auto category. Earlier this year, it unveiled its i8 sedan and i3 city car concepts, which are the first cars designed from the ground up as plug-in hybrids.

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Martin LaMonica is a senior writer covering green tech and cutting-edge technologies. He joined CNET in 2002 to cover enterprise IT and Web development and was previously executive editor of IT publication InfoWorld.
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